This invention relates generally to sealing rings and, more specifically, to sealing rings used in the flexible joinder of end portions of two opposed gas conduits for permitting gas flow therebetween during angular misalignment movement or offset, axial translation, axial rotation, and vibration of the conduits with a minimum of gas leakage.
Flexible coupling devices which employ sealing rings for joining gas or air conduits together in an effectively air tight or gas tight manner while permitting the previously mentioned types of movement of the adjoined conduits have, broadly speaking, long been known and used in the prior art. See, for example, the flexible couplings or sleeves and various sealing ring combinations used therewith as disclosed in U.S. Pat. No. 5,106,129 granted to L. A. Camacho et al. on Apr. 21, 1992. Another type of prior art coupling or sleeve (not including the rings shown therewith) for joining high pressure/high temperature air conduits together as used in the commercial air craft industry is shown at 12 in FIG. 1 of the accompanying drawings.
In commercial aircraft the sealing ring assemblies used in the ring housings of flexible coupling sleeves or in ring channels disposed between opposed, concentrically overlapping end portions of gas conduits of different diameters typically operate at air pressures from 40 to 70 psig at temperatures from ambient up to 350 to 500.degree. F. Silicone seal rings have typically been used for this purpose in the prior art. While such prior art seal rings have good flexibility when originally installed and operated at low temperatures of from ambient up to about 200.degree. F., they have a tendency to crack, become cracked and brittle and developed burned spots or areas when subjected to the typical high operating temperature range encountered in gas ducting or conduct systems of commercial jet engines. As a result, they actually suffer a loss of ring material, as through vaporization and become deformed so as to lose certain of their design dimensional characteristics. They also become set so that they can no longer adjust to relative movements of between two gas conduits being sealed by the rings in the sleeve housing or ring channel such that gas leakages occur past the rings.
Other materials, such as polytetrafluoroethylene and certain types of plastics do not encounter these problems in the 350 to 500.degree. F. operating temperature range as does silicone. However, these latter materials are ordinarily not sufficiently flexible to adjust well at low temperatures to vibratory and other movements between adjoined conduits and therefore have not previously been found to be useful as sealing rings in aircraft engine gas or air ducting systems.
By means of my invention, I have developed a sealing ring which can be made of such polytetrafluoroethylene and plastic material which has none of the problems encountered with silicone rings in the 350 to 500.degree. F. operating temperature range, yet is sufficiently flexible at all temperatures from ambient up to and through this typical high temperature range to provide excellent sealing characteristics for adjoined gas conduits which are subject to various vibratory and other movements relative to one another.